Electrical recording apparatus.



No. 642,674. Patented Feb. 6, I900. H. L. CALLENDAB.

ELECTRICAL RECORDING APPARATUS.

(Application filed Feb. 14, 1898.) (No Modei.) 1 Sheets-Shut I.

No. 642,674: Patented Feb. 6, I900; H. L. CALLENDAR.

ELECTRICAL RECORDING APPARATUS.

(Application filed Feb. 14, 1898.) (No Model.) 7 Sheets-Sheet 2.

fllffereipfz'al Pallgy.

G); W Q

L'L K Q HL FY /f -L EHO J. l w l vi 1 R C 0 C- a W M (!D No. 642,674. Patented Feb. 6, I900. H. L. CALLENDAR.

ELECTRICAL RECORDING APPARATUS.

(Application filed Feb. 14, 189B.)

1 Sheets$haat 3.

(No Model.)

miheauw 1m: norms vn'zn cu. womumo" wnsuwarou, n. r;v

No. 642,674. Patented Feb. 6, I900. H. L. CALLENDAB.

ELECTRICAL RECORDING APPARATUS.

(Application filed Feb. 14, 1898.) (No Model.) 7 Sheets-Sheet 4,

TIEYII? Patented Feb. 6, I900.

H. L. CALLENDAR.

ELECTRICAL RECORDING APPARATUS.

(no uud'e.) (Application filed Feb 14, 1898.) 7 sheets-Shae 5.

TIEJZ'IIL J L Z2 5 z A E h J m J m/ Firms 7 AA Z if; Q &

cams PEYERS ca. PHom-umu, WASHINGTON, n. c.

No. 642,674. P atented Feb. 6, I900. H. L. CALLENDAR. ELECTRICAL RECORDING APPARATUS.

* (Application filed Feb. 14, 1898.) (No Modal.) 7 Sheets-Sheet 6.

7726mm 1m No. 642,674. Patented Feb. 6, I900.

H. L. CALLENDAR. I

ELECTRICAL RECORDING APPARATUS.

(Application filed Feb. 14, 1898.) (No Model.) 1 Sheets-Sheet 7.

UNITED STATES PATENT OFFICE;

HUGH LONGI JOURNE OALLENDAR, OF MONTREAL, CANADA.

LECTRICAL RECORDING APPARATUS.

SPECIFICATION forming part of Letters Patent N 0. 642,674, dated February 6, 1900.

Application filed February 14, 189B. t crial No. 670,335. (No model.)

Toall whom it nut/y con/067%.

Be it known that I, HUGH LONGBOURNE OALLENDAR, a subject of the Queen of Great Britain, and a resident of McGill University, in the city of Montreal, Dominion of Canada, have invented new and useful Improvements in ElectricalRecordingApparatus, (for which I have filed an application for a patent in Great Britain, No. 16,718, dated July 14, 1897,) of which the following is a specification.

The method of recording electrical quantities herein described is directly applicable to those cases in which the measurement may be effected by sliding a contact-piece along the wire or other uniformly subdivisible resistance forming part of an electrical circuit until a point is found at which the value of the electric potential is the same as at some other given point. This equality of potential is ascertained by connecting a galvanometer or other suitable indicator between the points in question. The wire along which the readings are taken is called a bridge- Wire, and the point at which the current through the galvanometer is reduced to zero is called the -balance-point. The bridgewire is usually, but not necessarily, straight. Thus in cases where a higher resistance is required than can be obtained by the use of a straight wire a close insulated helix wound on a rod may be employed with fifty or one hundred turns to the inch. This is practically equivalent to a straight bridgewire, as the steps or subdivisions are so numerous as to give a nearly-continuous adjustment. By attaching a pen or other recording device to the contact-piece on the bridge-wire and by moving the contact in such a manner as to keep it always at the balance-point it is clear that the variations of the quantity to be measured may be recorded. The improvements herein described relate to means by which the contactis automatically maintained always at the balance-point to the adjustment of the scale of the record and the con:

struction of the apparatus in such a manner as to make the application as general and accurate as possible.

In order that my invention may be fully understood, I will proceed to describe it with reference to the accompanying drawings, in which Figure I is aiplan, and Fig. II an elevation, of the galvanometer arm and contacts. Figs. III and IV are a diagrammatic front elevation and end view of the instrument, showing the electrical connections. Fig. V is a diagram showing one arrangementof the driving-pulleys. Fig. VI is a diagram of a thermometer for measuring the voltage of alternating currents. Figs. VII and VII, Sheets 2 and 3, show a front elevation. Fig. VIII is a vertical section showing the mechanical construction of the instrument. Figs.,IX and X are diagrams showing the electrical connections in two special cases.

In order to maintain the balance automatically, the galvanometer, which is preferably one of movable-coil type, is provided with an arm called the relay-arm, which actuates one or other of two electric circuits, accord ing as the galvanometer deflects to one side or the other. The circuit so actuated starts a motor, which tends to restore the contactpiece to its position of balance. To prevent sticking of the relay-contacts and to secure sufficient delicacy of action, the stop or stops with which the relay-arm makes contact are kept in a continual sliding motion, the contact-surfaces are also continually cleansed by the action of suitable scrapers,and the relayarm itself is kept in a'state of gentle oscillation by means of a fan. The contact-stop is preferably made in the form of a slightly-eccentric wheel revolving by clockwork and scraped on either side by a pair of light metal springs. The relay-arm 1 in Figs. I and II is shown with a pair of contacts 2 3, forming a fork oneither side of the single contact-wheel 4; but it is equally possible to use a pair of contactwheels on either side of a single contact-point on the relay-arm. Scrapingsprings of suitable form are shown at 5. The contact-wheeld is shown fixed to the spindie 15 of the seconds-hand of an ordinary lever-clock. The oscillating lever 16 of the escapement of this clock has fixed to it a small light plate 17, forming the fan, by which the arm 1 is kept in a state of oscillation. This fan is only necessary when extreme sensitiveness is required. The clearance between the wheel 4 and the contacts 2 and 3 is, say, one two-hundredth of an inch, and therefore the arm 1, if normally at rest, would have to be deflected through that distance before any indication was given; but if the arm oscillates the contacts 2 and 3 alternately and momentarily touch the wheel 4. These contacts are so instantaneous that they produce little effect, and when the arm is normally central the effects are equal and balance each other; but if the arm 1 be deflected by the galvanometer,however slightly,the times during which the contacts with 2 and 3, respectively, last are no longer equal, and the effects, therefore, do not balance each other, and the effects produced by the difference are cumulative. In this way a deflection of the arm 1 greatly less than one two-hundredths of an inch is recorded. 1

The bridge-wire shown in Figs. III and VII is soldered at the ends to short pieces of thick wire A and B, which are held by set-screws A B in the insulating-blocks EG FH.

The bridge-wire itself is made of platinum silver or other suitable material having a resistance of one or two ohms per meter or more, if desired. Its resistance is adjusted to an exact value by shunting it with a resistance S of similar material, which is adjusted so that the scales of different instruments may be commensurable. The bridge-wire may also take the form of a close spiral. The thick wires A and B at either end serve for making connections and also for adjusting the zeropoint of the wire with reference to the scale on the recording-sheets. For this purpose it is only necessary to slacken the set-screws and move the wire endwise. When the bridge-wire is connected on the principle of potentiometer, as described below, it is frequently desirable that the zero-point corresponding to zero difference of potential should be at the center of the wire. It would not be always easy or convenient to make a connection to the center of the bridge-wire itself. The same effect is secured in a simple and exact manner by making connection to the middle point of the shunt S. Connection is madebetween the bridge-wire and the galvanometer by means of a wire of similar material C D, which is called the galvanometer-wire and is stretched alongside the bridge-wire. The sliding contact is preferably made by means of light springs carrying short pieces or rollers of platinum iridium, as shown at M N. These springs serve also to maintain a suitable pressure of the point of the recording-pen P on the revolvingdrum 0, Figs. VII, VII, and VIII. The pen and the contact-springs are attached to a sleeve KL, which slides along rod EF. The tension of the bridge-wire and galvanometerwire is maintained uniform by means of the metallic rods EF and GH, which are clamped in the insulating-blocks EG FH, but free to slide through holes in the block RT. The blocks EG RT are fixed to the base of the instrument; but the block FH is free to slide. The traveling sleeve is provided with stops K and L, which engage with small springswitches V and W at either end of the travel.- The switches V and WV serve to break either electric circuit automatically and to prevent the recording-point being carried off the limits of the scale, while leaving it free to return under the action of the opposite motor.

The mechanism for moving the contactpieee on the bridge-Wire in either direction according to the deflection of the galvanometer preferably consists of a pair of clock-motors connected by means of a suitable difien ential gear. This mechanism is shown in Figs. VII, VII, and VIII. a b are a pair of electromagnets whose armatures a, b are pivoted at a b and carry counterbalanceweights a b and have at their lower ends strips a 19 which serve as brakes acting 011 brake-wheels c d, which are thus normally held stationary. These brake-wheels form part of two ordinary clock-trains without escapements, so that immediately one or other of the brakes is lifted by the magnet a or b attracting its armature the clock-train start-s. The movement of the relay-arm 1 in either direction, as shown in diagrams IX and X, closes a circuit from the battery 6 through one or other of the magnets ab, and this starts one or other clock-train, as above described. f and g are the last pinions of the clocktrains, and these gear with wheels h andj, fixed to sleeves hj, Fig. VIII, loose on the spindle 7a. 71 3' are other wheels also fixed to the sleeves, and these gear with two pinions 2 Z, which also gear together. The pinions Z Z are carried by a frame Z fixed to the spindle 7c and provided with a eounterbah ance-weight Z The action is as follows: If the magnet a attracts its armature, the brakewheel 0 and the wheel 71. commence to rotate, while the wheel j remains stationary, since the wheel (Z is still held by its brake. The

revolution of the wheel k drives the pinions Z and Z, the latter rolling around the stationary wheelj and the frame Z and spindle k are thus slowly rotated. The spindle 7.; is in like manner rotated, but in the opposite direction, when the magnet 12 attracts its armature. The spindle 7c has fixed to it a pinion 7t, gearing with a wheel m", fixed to the drum or pulley m, around which passes the cord 72, whose end is fixed to the spring K L. The same effect may also be produced by means of the differential system of pulleys shown in Fig. V. In this diagram, 6 and 7 represent pulleys connected to the clock-motors so as to turn with suitable speed and power when the motors are released by the corresponding electromagnets. 8 and f) are the differential pulleys. 10 is an idle pulley attached to a spring for keeping the necessary tension on the cord. An endless cord passes around the pulleys 6 8 7 9 in order,as shown. The pulleys 8 and 9 are connected by a cord passing around the pulley 10. It is plain on inspection that if the motor 6 starts to turn the pulley 9 is moved to the right and pulley S to the left, but that if the motor 7 starts in the same IlO direction the Opposite takes place. The con tact-piece on the bridge-wire may be connected to either of the pulleys 8 or 9, provided that the galvanometer connections are made to correspond.

Connected to one end of the bridge-wire are a series of auxiliary resistances XYZ, &c., which are adjusted to represent 10, 2O," a0, &c., or other suitable numbers of divisions of the scale of the bridge-wire. These resistances serve for extending the scale of the bridge-wire in the usual manner and are provided with plugs or screw-nuts, by means of which they can be short-circuited. For resistance measurements on the Wheatstonebridge method a pair of ratio-coils QJ JU is also added. The galvanometer is then connected at J and M and the resistance to be measured at I and U. The place of these resistances may be supplied, if preferred, by ordinary commercial resistance-boxes. They are not-essential parts of the apparatus; but

it is generally convenient to include them in the same box.

The recording apparatus above described may be used for a variety of very different purposes without any modification in its essential features by connecting it to different pieces of apparatus or different electric circuits according to methods which are well understood. It is necessary, however, to specify these applications in order that some other inventor may not claim the combination as being a separate and distinct inven tion.

If the bridge-wire is connected, as shown in Fig. IX, in series with auxiliaryresistances and suitable rheostat to constant battery 0, the instrument may be used as a potentiometer for recording variations of electric potential. The difference of electric potential to be recorded would then be applied to the zero-point p on the auxiliary resistance or shunt and to the free terminal of the galvanometer q, (one terminal being already connected to the contact-point M on the bridgewire.) The difference of potential to be measured may be that produced by a thermocouple r, in which case the record represents variations of temperature, or may be some suitable fraction of the electric pressure on a direct-current lighting or power circuit, in which case the record gives directly the variations of the electric pressure. Variations of current may be similarly recorded by the usual method of measuring the difference of potential on a known resistance through which the current is passed.

In order to record rapid cyclical variations of potential or current in the same manner, it is only necessary to include a periodic contact in the galvanometer-circuit to complete the circuit at a definite point of the cycle. If the point of the cycle corresponding to the position of the contact-brushes be slowly and uniformly shifted, the recording-pen will trace the curve of the cycle. The forms of alternating current and potential curves of dynamo machines may be automatically traced in this manner. By means of a suitable thermopile the cyclical variations of temperature in the walls of the cylinder of a steam or other heat engine may be similarly recorded. In recording cyclical variations of this nature it is convenient to connect the difference of potential to the middle point of the shunt in order that the zero maybe at" the center of the bridge-wire, as explained above. I A wide range of applications of this recording system is afforded by applying the instrument to record variations of electrical resistance. For this purpose the bridge-wire is connected on the Wheatstone-bridge method,

as explained above. A battery 0 is connected to the points Q U, as shown in Fig. X. This battery may conveniently be the same asthat used for actuating the relay-circuit. If the resistance to be measured consists of an electrical resistance-thermometer s, the record will represent the variations of temperature of the thermometer and may be made-to cover any desired range or to suit any desired purpose by choosing a thermometer of suitable resistance and construction. If an alternating difference of potential be simultaneously applied to the thermometer and the wire be sufficiently fine to be heated by the current, the recorded variations of temperature of the resistance-thermometer will give the variations of the alternating voltage. The variations of the alternating current may be recorded in a similar manner by passingv the current or some suitable fraction thereof, through the wire of the thermometer. For this purpose it is convenient to make the thermometer consist of two wires in parallel, as shown in Fig. VI, and to connect the alternating-current terminals 11 12 to the center of each wire, so that the alternating current will not pass through the other resistances, forming the Wheatsone bridge, to which the thermometer is connected at 13 14. If the resistance consists of a fine platinum wire in a vertical tube containing mercury, changes of level of the mercury will alter the length of wire exposed, and may therefore be recorded by the same apparatus. This application is useful for recording variations of barometric or steam pressure and variations of waterlevel, &c. If a pair of differential electrical thermometers be connected on either side of the bridge-wire, the record will give the difference of temperature. It is thus possible to record in a single curve the difference of temperature, for instance, between two stations at different altitudes or between the wet and dry bulb thermometers. Again, if one of the wires be blackened and both be exposed to radiation, such as sunshine or the radiation of a furnace, the record represents the intensity of radiation of the sun or of the furnace. It should be observed that all these different records may be obtained by means of one single instrument by single changes in the electrical connections and in the apparatus with which it is associated.

The auxiliary pieces of apparatus, such as platinum thermometers, &c., are separate attachments, and do not form essential parts of the apparatus. It is possible to use one single recording instrument in turn for all the different purposes specified.

I do not show a special description of the planimeter attachment for totalizing, which merely amounts to replacing the pen by wheel rolling on a cone or disk. The pen and the planimeter-roller may be combined in one, the curve-record being traced on the revolving disk by inking the roller of the planimeter, or both pen and planimeter may be sep arate, moving on separate surfaces, but both actuated by a common cord. These details, which are common to so many instruments, are claimed in the combination with my special recording mechanism.

Having thus described my invention, the following is what I claim as new therein and desire to secure by Letters Patent:

1. The combination of a bridge-wire, a contact movable along it, a recording device carried by the contact, a galvanometer, means for connecting its poles to the bridge-wire and to the contact, and means actuated by the galvanometer for traversing the contact.

2. The combination of a bridge-wi re, a contact movable along it, a recording device carried by the contact, a shunt, means for connecting its ends to the ends of the bridgewire, a galvanometeigdneans for connecting its poles to the shunt and to the contact, and means actuated by the galvanometer for traversing the contact.

3. The combination of a bridge-wire, a contact movable along it, a recording device carried by the contact, a galvanometer, means for connecting its poles to the bridge-wire, and to the contact, a series of auxiliary resistances, means for connecting them to the bridge-wire or resistance, and means actuated by the galvanometer for traversing the-contact.

4. The combination of a bridge-wire, a contact movable along it, a recording device carried by the contact, a shunt, means for connecting its ends to the ends of the bridgewire, a galvanometer, means for connecting its poles to the shunt and to the contact, a series of auxiliary resistances, means for connecting them to the bridge-wire, and means actuated by the galvanometer for traversing the contact.

5. The combination of a bridge-wire, a second wire parallel to it, a pair of contacts connected together and movable along the bridge-wire and the second wire, a recording device carried by the contacts, a galvanometer, means for connecting its poles to the bridge-wire and to the second wire, and means actuated by the galvanometer for traversing the contacts.

mast-4i 6. The combination of a bridge-wire, a second wire parallel to it, a pair or" contacts connected together and movable along the bridge-wire and the second wire, a recording device carried by the contacts, a shunt, means for connecting its ends to the ends of the bridge-wire, a galvanometer, means for connecting its poles to the shunt and to the second wire, and means actuated by the galvanometer for traversing the contacts.

7. The combination of a bridge-wire, a sec ond Wire parallel to it, a pair of contacts connected together and movable along the bridge-wire and the second wire, a recording device carried by the contacts, a galvanometer, means for connecting its poles to the bridge-wire and to the second wire, a series of auxiliary resistances, means for connecting them to the bridge-wire, and means actuated by the galvanometer for traversing the contacts.

8. The combination of a bridge-Wire, a second wire parallel to it, a pair of contacts connected together and movable along the bridge-wire and the second wire, a recording device carried by the contacts, a shunt, means for connecting its ends to the ends of the bridge-wire, a galvanometer, means for connecting its poles to the shunt and to the second wire, a series of auxiliary resistances, means for connecting them to the bridge-wire, and means actuated by the galvanometer for traversing the contacts.

9. In an electrical recording apparatus the combination of a galvanometer-arm, means whereby it is kept in a state of gentle oscillation, a pair of contactsuriaces carried by it and a second pairof contact-surfaces against which the first pair work.

10. In an electrical recording apparatus the combination of a galvanometer-arm, means whereby it is kept in a state of gentle oscillation, a pair of contact-surfaces carried by it, a second pair of cont-act surfaces against which the first pair work, means for rotating the second pair of surfaces and scrapers acting on them.

11. In an electrical recording apparatus, the combination of a galvanometer-arm, a pair of contact-surfaces carried it, a second pair of contact-surfaces against which the first pair work, means for rotating the second pair of surfaces and scrapers acting on them.

12. In an electrical recording apparatus, the combination of a galvanometer, a recording device, and a pair of motors controlled by the galvanometer and tending to move the recording device one in one direction and the other in the other.

13. In an electrical recording apparatus, the combination of a galvanometer, a recording device, a pair of clock motors tending to move the recording device one in one direction and the other in the other, brakes tending to stop the motors, and means operated by the galvanometer for taking off the brakes.

14. In an electrical recording apparatus, the

combination of a galvanometer, a recording device, a pair of motors tending to move the recording device one in one direction and the other in the other, circuits closed by the galvanometer and controlling the motors, and switches in the circuits one at each end of the travel of the recording device and operated by it.

15. The combination of a bridge-wire movable longitudinally, means for clamping it in position, a contact movable along it, a recording device, a galvanometer, means for connecting its poles to the bridge-Wire and to the contact, and means actuated by the galvanometer for traversing the contact.

16. The combination of an electrical recording apparatus, substantially as described, with a constant battery and a series of auxiliary resistances connected according to the potentiometer method, for recording variations of voltage or current on a direct-current circuit, or for recording variations of temperature by means of a thermocouple or thermopile.

17. The combination of abridge-Wire, a c011- tact movable along it, a recording device carried by the contact, a galvanometer, means for connecting its poles to the bridge-wire and to the contact, a pair of clock-motors tending to move the contact in opposite directions, brakes tending to stop the motors, and means operated by the galvanometer for taking off the brakes.

18. The combination of abridge-wire, a contact movable along it, a recording device carried by the contact, a shunt, means for connecting its ends to the ends of the bridgewire, a galvanometer,'means for connecting its poles to the shunt and to the contact, a pair of clock-motors tending to move the contact in opposite directions, brakes tending to stop the motors, and means operated by the galvanometer for taking off the brakes.

19. The combination of a bridge-Wire, a contact movable along it, a recording device carried by the contact, a galvanometer, means for connecting its poles to the bridge-Wire and to the contact, a series of auxiliary resistances, means for connecting them to the bridge-wire, a pair of clock-motors tending to move the contact in opposite directions, brakes tending to stop the motors, and means operated by the galvauometer for taking ofif the brakes.

20. The combination of abridge-wire, a contact movable along it, a recording device carried by the contact, a shunt, means for connectingits' ends to the ends of the bridge-Wire, a galvanometer, means for connecting its poles to the shunt and to the contact, a series of auxiliary resistances, means for connecting them to the bridge-wire, a pair of clock-motors tending to move the contact in opposite directions, brakes tending to stop the motors,

and means operated by the galvanometer for taking off the brakes.

21. The combination of a bridge-wire, a second Wire parallelto it, a pair of contacts connected together and movable along the bridge- Wire and the second Wire, a recording device carried by the contacts, a galvano'meter, means for connecting its poles to the bridge- Wire and to the second Wire, a pair of clockmotors tending to move the contacts in opposite directions, brakes tending to stop the motors, and means operated by the galvanometer for taking oit the brakes.

22. The combination of abridge-Wire, a second Wire parallel to it, a pair of contacts connected together and movable along the bridgewire and the second wire, a recording device carried by the contacts, a shunt, means for connecting its ends to the ends of the bridgewire, a galvanometer, means for connecting its poles to the shunt and to the second Wire, a pair of clock-motors tending to move the contacts in opposite directions, brakes tending to stop the motors, and means operated by the galvanometer for taking oi? the brakes.

23. The combination of a bridge-wire, a second Wire parallel to it, a pair of contacts connected together and movable along the bridgewire and the second Wire, a recording device carried by the contacts, a galvanometer, means for connecting its poles to the bridge- Wire or resistance and to the second Wire, a series of auxiliary resistances, means for connecting them to the bridge-Wire, a pair of clock-motors tending to move the contacts in opposite directions, brakes tending to stop the motors, and means operated by the gal vanometer for taking off the brakes.

24. The combination of a bridge-Wire, a sec ond- Wire parallel to it, a pair of contacts connected together and movable along the bridge- Wire and the second Wire, a recording device carried by the contacts, a shunt, means for connecting its ends to the ends of the bridge- Wire, a galvanometer, means for connecting its poles to the shunt and to the second wire, a series of auxiliary resistances, means for connecting them to the bridge-Wire, a pair HUGH LONGBOURNE CALLENDAR.

In presence of HENRY FRY, RoNZo H. CLARK. 

